Computing devices are designed to communicate with their users. Historically, this communication has been provided by a visual and audible presentation of information, such as via a screen or a speaker. When a need arises to capture the attention of a computing device user, for example, to alert the user of information that is relevant to the user at a given time, typical methods to grab the user's attention include visual alerts, such as pop-up notifications displayed on a screen, or audible signals, such as beeps, bells, or spoken announcements played through the device's speaker.
Computing device users are increasingly using text narration for a variety of tasks. For example, users with vision impairments may use assistive technology, such as a screen reader to narrate or echo textual content. As another example, mobile users may use text narration in situations where looking at a screen is not desirable, such as when driving a car or engaging in another activity.
While visual or audible notifications are effective in many applications, there are many other applications where visual or audible notifications may be impractical or distracting to the user. Providing visual or audible notifications when it is impractical or distracting to the user degrades the user's experience with the device, and can result in a user experiencing reduced functionality of the device. For example, oftentimes, it is desirable to notify a content narration user of meta-information in a document, wherein meta-information includes information that is related to content that is being narrated, but that is not directly part of content (e.g., co-author presence, hyperlinks, footnotes, endnotes, cross-references, comments, formatting, tracked changes, spelling or grammatical errors, contextual information). However, visual notifications may be impractical or ineffective, such as with visually-impaired users. Further, adding audible content to audio output, such as by narrating meta-information or playing audible alerts, can be disruptive or overwhelming to the user. For example, the users may lose their trains of thought or may not be able to clearly hear the narrated content.